Manipulator

ABSTRACT

A manipulator for an environment with hygienic requirements, comprising a stationary element ( 1 ) with a plurality of drive means ( 2 ), and arms ( 3 ) attached to the drive means, which arms, via a respective linkage ( 4 ), support a movable element ( 5 ). The drive means ( 2 ) are enclosed in an enclosure ( 6 ) which encloses a gaseous coolant which, by a forced flow, takes up heat from the motors of the drive means.

TECHNICAL FIELD

The invention relates to a manipulator which, with the assistance of acontrol unit, forms an industrial robot for primarily picking purposes.In particular, the invention relates to a manipulator with three arms bymeans of which a movable member, comprised in the manipulator, isbrought to arbitrary positions in space with retained orientation andinclination.

BACKGROUND ART

An industrial robot comprises a manipulator and control equipment,whereby the manipulator with the assistance of the control equipmentcarries out arbitrary operations within a working range. Usually, such amanipulator comprises a plurality of arms which support a hand, on whicha tool is arranged. In the majority of robot applications, a traditionalsix-axis manipulator is used, which exhibits sufficient movability tocarry out a wide range of operations with mostly very high accuracy. Forcertain applications, however, there is a need of a manipulator whichhas fewer degrees of freedom but which permits faster operations. Such amanipulator may be mechanically connected in such a way that thetool-carrying hand is all the time oriented in space in a predeterminedmanner.

From U.S. Pat. No. 4,976,582 a manipulator is previously known by meansof which a movable element in relation to a stationary element may bemoved in a space with retained orientation and retained inclination. Themanipulator has three arms which jointly support the movable element.Each of these arms is rotatably journalled in the stationary elementaround a respective first axis. The arm supports a linkage, one end ofwhich is rotatably journalled in the outer part of the arm, allowing amovement in two degrees of freedom. In its other end, the linkagesupports the movable element and is journalled therein, allowing amovement in two degrees of freedom.

The linkage comprises two parallel links and is arranged, together withthe arm, such that one of the degrees of freedom of each end of thelinkage constitutes a rotation around an axis which is parallel to thefirst axis of the respective arm. Irrespective of the movements of thearm or the linkage, these three axes of rotation are thus kept inparallel. In this way, the movable element will always have the sameorientation and inclination in relation to the stationary element. Onecondition, however, is that the respective first axes of the arms forman angle with each other.

When working in spaces where there are hygienic requirements, amanipulator may not emit any smell, fluid or dirt which may causesanitary inconvenience in this space. Activities in such spaces oftengive off dirt and fluids which accumulate on the manipulator and whichare then emitted therefrom. The known manipulator has an open designwith a plurality of components. All movable components including thedrive means with their motors must be lubricated. In that context, it isunavoidable that lubricant and accumulated dirt are, at some time,emitted from the manipulator. This makes the known manipulator lesssuitable for use in spaces where hygienic requirements are made.

SUMMARY OF THE INVENTION

The object of the present invention is to suggest ways and means ofmanufacturing a manipulator of the kind described above, which isarranged such that it may be used in spaces with hygienic requirements.The manipulator shall be prevented from giving off smell, fluid or dirt.The manipulator shall be capable of being flushed and still capable ofdiverting heat given off by the drive means. During start-up of themanipulator in a cold space, the drive means shall be capable of beingpreheated.

These objects are achieved according to the invention by a manipulatoraccording to the characteristic features described in the characterizingportion of the independent claim 1 and with a method according to thecharacteristic features described in the characterizing portions of theindependent claims 6 and 9. Advantageous embodiments are described inthe characterizing portions of the dependent claims.

According to the invention, the above-mentioned objects are achieved byarranging an enclosure forming a closed system surrounding the drivemeans of the manipulator. Within this enclosure, a coolant, which may beair, is pressed through the motors of the drive means. The coolant thendelivers the absorbed heat to an external cooling system. During coldstart of the manipulator, heat is instead supplied to the motors via thecoolant.

The enclosure is closed with such a tightness that it is capable ofbeing flushed without liquid penetrating into the enclosure and therecausing damage to the manipulator. The whole manipulator including theenclosure is formed with smooth surfaces without folds or pockets whichmay attract dirt. Dirt or liquid, given off from the motors, iscollected within the enclosure.

BRIEF DESCRIPTION OF THE DRAWING

The invention will be explained in greater detail by description of anembodiment with reference to the accompanying drawing showing athree-dimensional view of a manipulator according to the invention, inwhich the drive means are enclosed in an enclosure.

DESCRIPTION OF THE PREFERRED EMBODIMENT

The manipulator shown in the FIGURE comprises a stationary element 1, towhich three drive means 2 (concealed) are attached. To each drive meansthere is attached an arm 3 which, via a linkage 4, supports a movableelement 5. The three arms with their linkages are identical in theexample, and therefore only one of the three arms has been provided withreference numeral. The three drive means are enclosed within anenclosure 6 which has a lower section 7 and an upper section 8. Thelower section is arranged such that liquid and dirt, possibly emittedfrom the drive means and their motors, are collected inside theenclosure.

Inside the enclosure, a coolant circulates, in the example shownconsisting of gas, for example air. The upper section 7 comprises anoutlet for supply air 9 and an outlet for exhaust air 10. In the exampleshown, exhaust air and supply air are interconnected by an external duct11. This results in a closed cooling system for the drive means andtheir motors. A fan (not shown) presses air through the motors insidethe enclosure. The air absorbs heat from the motors and circulates itfurther through the external duct. The external duct is adapted tocomprise a cooling device (not shown). Such a cooling device may be aheat exchanger which is traversed by an outer coolant, which may be aliquid. The air passing through the duct then gives off its absorbedheat to the outer coolant. There is nothing preventing arranging theventilation in the enclosure into a larger system common to severalmanipulators. However, such a ventilation system should be closed inrelation to the space where the manipulator is working.

By enclosing the drive means of the manipulator, in this way, in anenclosure which is tight relative to the space where the manipulator isworking, the manipulator may be used for operations in environmentsinvolving high hygienic requirements. In an advantageous embodiment, theenclosure is capable of being flushed, so that it may easily be cleanedwithout liquid penetrating into the enclosure and there causing damageto the manipulator. A tight enclosure implies that the motors of thedrive means must be supplied with a cooling effect during operation.Otherwise, the motors get overheated, ultimately resulting in breakdown.The forced cooling described above is thus necessary in case of acompletely tight enclosure.

By arranging a heat exchanger in the cooling duct, the air circulatinginside the enclosure may be rapidly cooled. This makes it possible tokeep the motors at a correct working temperature, regardless of theload. The heat exchanger and the forced cooling may also advantageouslybe used for putting the manipulator into operation. In certain cases,the manipulator is placed in a cold space. During an interruption, forexample overnight, the whole manipulator including the motors becomecooled. At a lower temperature, lubricant is viscous and does not havethe same lubricating ability as at warmer temperatures. The cooledmanipulator must then be started with slow movements such that thelubrication is ensured. According as the motors give off heat, thelubricant is heated and the speed of the manipulator may increase.During such cold starts, the cooling system may instead, somewhat beforethe putting into operation, supply the motors with hot air which isheated via the heat exchanger. In this way, the manipulator may bestarted with full performance even during start-up.

What is claimed is:
 1. A manipulator for an environment with hygienic requirements, comprising a stationary element with a plurality of drive means, and arms attached to the drive means, said arms, via a respective linkage, supporting a movable element, the manipulator further comprising an enclosure forming a closed cooling system containing gaseous coolant and surrounding the drive means, the coolant taking up heat from the motors of the drive means by a forced flow.
 2. A manipulator according to claim 1, wherein the enclosure is sealed over the drive means for collecting fluid and dirt from the drive means.
 3. A manipulator according to claim 1, wherein the coolant comprises air which, by the force from a fan, passes through the motors of the drive means.
 4. A manipulator according to claim 1, wherein means are provided to permit the coolant to circulate through a heat exchanger which transfers heat from the coolant to an outer coolant.
 5. A method for manufacturing a manipulator for an environment with hygienic requirements, including a stationary element with a plurality of drive means, and arms attached to the drive means, said arms, via a respective linkage, supporting a movable element, comprising the steps of surrounding the drive means by an enclosure which forms a closed cooling system, filling the enclosure with a gaseous coolant, and using the coolant to take up heat from the motors of the drive means by a forced flow.
 6. A method for manufacturing a manipulator according to claim 5, comprising the further step of using the enclosure to collect fluid and dirt from the drive means, the coolant comprising air which is pressed by a fan through the motors of the drive means.
 7. A method for manufacturing a manipulator according to claim 6, comprising the step of circulating the coolant through a heat exchange where heat from the coolant is transferred to an outer coolant.
 8. A method for putting into operation a manipulator for an environment with hygienic requirements including a stationary element with a plurality of drive means and arms attached to the drive means, said arms, via respective linkages, supporting a movable element, comprising the steps of surrounding the drive means to by an enclosure forming a closed cooling system, filling the enclosure with a gaseous coolant, and using the coolant, before the manipulator is started, to give off heat to the motors of the drive means by a forced flow. 